{"cve":"CVE-2021-21291","nvd":{"published":"2021-02-02T19:15:14.330","modified":"2026-06-17T03:35:12.840","status":"Modified","description":"OAuth2 Proxy is an open-source reverse proxy and static file server that provides authentication using Providers (Google, GitHub, and others) to validate accounts by email, domain or group. In OAuth2 Proxy before version 7.0.0, for users that use the whitelist domain feature, a domain that ended in a similar way to the intended domain could have been allowed as a redirect. For example, if a whitelist domain was configured for \".example.com\", the intention is that subdomains of example.com are allowed. Instead, \"example.com\" and \"badexample.com\" could also match. This is fixed in version 7.0.0 onwards. As a workaround, one can disable the whitelist domain feature and run separate OAuth2 Proxy instances for each subdomain.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-601"],"references":["https://github.com/oauth2-proxy/oauth2-proxy/commit/780ae4f3c99b579cb2ea9845121caebb6192f725","https://github.com/oauth2-proxy/oauth2-proxy/releases/tag/v7.0.0","https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-4mf2-f3wh-gvf2","https://pkg.go.dev/github.com/oauth2-proxy/oauth2-proxy/v7","https://github.com/oauth2-proxy/oauth2-proxy/commit/780ae4f3c99b579cb2ea9845121caebb6192f725"],"products":["oauth2_proxy_project:oauth2_proxy"],"source":"nvd","synced_at":"2026-10-19T21:14:10.479542811+00:00"},"epss":{"cve":"CVE-2021-21291","score":0.01595,"percentile":0.75735,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-4mf2-f3wh-gvf2","url":"https://osv.dev/vulnerability/GHSA-4mf2-f3wh-gvf2","summary":"Subdomain checking of whitelisted domains could allow unintended redirects in oauth2-proxy","modified":"2026-09-10T03:49:04.327848096Z","packages":[{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy/v7","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy/v7","ranges":["<7.0.0"],"fixed":["7.0.0"]},{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy","ranges":["<=3.2.0"],"fixed":[]}]},{"id":"GO-2022-0790","url":"https://osv.dev/vulnerability/GO-2022-0790","summary":"Subdomain checking of whitelisted domains could allow unintended redirects in oauth2-proxy in github.com/oauth2-proxy/oauth2-proxy","modified":"2026-03-03T04:50:53.714629Z","packages":[{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy/v7","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy/v7","ranges":["<7.0.0"],"fixed":["7.0.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}